Rollup merge of #97759 - WaffleLapkin:recover_label_expr, r=compiler-errors
Suggest adding `{}` for `'label: non_block_expr` Adds suggestions like this: ```text help: consider enclosing expression in a block | 3 | 'l {0}; | + + ``` inspired by https://github.com/rust-lang/rust/issues/48594#issuecomment-1146744400 r? ``@compiler-errors``
This commit is contained in:
commit
554674b98c
@ -13,10 +13,13 @@ use rustc_ast::tokenstream::Spacing;
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use rustc_ast::util::classify;
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use rustc_ast::util::literal::LitError;
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use rustc_ast::util::parser::{prec_let_scrutinee_needs_par, AssocOp, Fixity};
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use rustc_ast::visit::Visitor;
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use rustc_ast::StmtKind;
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use rustc_ast::{self as ast, AttrStyle, AttrVec, CaptureBy, ExprField, Lit, UnOp, DUMMY_NODE_ID};
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use rustc_ast::{AnonConst, BinOp, BinOpKind, FnDecl, FnRetTy, MacCall, Param, Ty, TyKind};
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use rustc_ast::{Arm, Async, BlockCheckMode, Expr, ExprKind, Label, Movability, RangeLimits};
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use rustc_ast_pretty::pprust;
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use rustc_data_structures::thin_vec::ThinVec;
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use rustc_errors::{Applicability, Diagnostic, DiagnosticBuilder, ErrorGuaranteed, PResult};
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use rustc_session::lint::builtin::BREAK_WITH_LABEL_AND_LOOP;
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use rustc_session::lint::BuiltinLintDiagnostics;
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@ -1548,9 +1551,66 @@ impl<'a> Parser<'a> {
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Ok(self.mk_expr_err(lo))
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} else {
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let msg = "expected `while`, `for`, `loop` or `{` after a label";
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self.struct_span_err(self.token.span, msg).span_label(self.token.span, msg).emit();
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let mut err = self.struct_span_err(self.token.span, msg);
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err.span_label(self.token.span, msg);
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// Continue as an expression in an effort to recover on `'label: non_block_expr`.
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self.parse_expr()
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let expr = self.parse_expr().map(|expr| {
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let span = expr.span;
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let found_labeled_breaks = {
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struct FindLabeledBreaksVisitor(bool);
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impl<'ast> Visitor<'ast> for FindLabeledBreaksVisitor {
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fn visit_expr_post(&mut self, ex: &'ast Expr) {
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if let ExprKind::Break(Some(_label), _) = ex.kind {
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self.0 = true;
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}
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}
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}
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let mut vis = FindLabeledBreaksVisitor(false);
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vis.visit_expr(&expr);
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vis.0
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};
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// Suggestion involves adding a (as of time of writing this, unstable) labeled block.
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//
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// If there are no breaks that may use this label, suggest removing the label and
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// recover to the unmodified expression.
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if !found_labeled_breaks {
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let msg = "consider removing the label";
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err.span_suggestion_verbose(
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lo.until(span),
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msg,
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"",
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Applicability::MachineApplicable,
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);
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return expr;
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}
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let sugg_msg = "consider enclosing expression in a block";
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let suggestions = vec![
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(span.shrink_to_lo(), "{ ".to_owned()),
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(span.shrink_to_hi(), " }".to_owned()),
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];
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err.multipart_suggestion_verbose(
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sugg_msg,
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suggestions,
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Applicability::MachineApplicable,
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);
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// Replace `'label: non_block_expr` with `'label: {non_block_expr}` in order to supress future errors about `break 'label`.
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let stmt = self.mk_stmt(span, StmtKind::Expr(expr));
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let blk = self.mk_block(vec![stmt], BlockCheckMode::Default, span);
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self.mk_expr(span, ExprKind::Block(blk, label), ThinVec::new())
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});
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err.emit();
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expr
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}?;
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if !ate_colon && consume_colon {
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@ -47,6 +47,12 @@ error: expected `while`, `for`, `loop` or `{` after a label
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LL | 'l4 0;
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| ^ expected `while`, `for`, `loop` or `{` after a label
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help: consider removing the label
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LL - 'l4 0;
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LL + 0;
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error: labeled expression must be followed by `:`
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--> $DIR/labeled-no-colon-expr.rs:8:9
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27
src/test/ui/parser/recover-labeled-non-block-expr.fixed
Normal file
27
src/test/ui/parser/recover-labeled-non-block-expr.fixed
Normal file
@ -0,0 +1,27 @@
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// run-rustfix
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#![feature(label_break_value)]
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fn main() {
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let _ = 1 + 1; //~ ERROR expected `while`, `for`, `loop` or `{` after a label
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match () { () => {}, }; //~ ERROR expected `while`, `for`, `loop` or `{` after a label
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'label: { match () { () => break 'label, } }; //~ ERROR expected `while`, `for`, `loop` or `{` after a label
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#[allow(unused_labels)]
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'label: { match () { () => 'lp: loop { break 'lp 0 }, } }; //~ ERROR expected `while`, `for`, `loop` or `{` after a label
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let x = 1;
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let _i = 'label: { match x { //~ ERROR expected `while`, `for`, `loop` or `{` after a label
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0 => 42,
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1 if false => break 'label 17,
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1 => {
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if true {
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break 'label 13
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} else {
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break 'label 0;
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}
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}
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_ => 1,
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} };
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let other = 3;
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let _val = 'label: { (1, if other == 3 { break 'label (2, 3) } else { other }) }; //~ ERROR expected `while`, `for`, `loop` or `{` after a label
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}
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@ -1,5 +1,27 @@
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// run-rustfix
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#![feature(label_break_value)]
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fn main() {
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'label: 1 + 1; //~ ERROR expected `while`, `for`, `loop` or `{` after a label
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let _ = 'label: 1 + 1; //~ ERROR expected `while`, `for`, `loop` or `{` after a label
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let _recovery_witness: () = 0; //~ ERROR mismatched types
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'label: match () { () => {}, }; //~ ERROR expected `while`, `for`, `loop` or `{` after a label
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'label: match () { () => break 'label, }; //~ ERROR expected `while`, `for`, `loop` or `{` after a label
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#[allow(unused_labels)]
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'label: match () { () => 'lp: loop { break 'lp 0 }, }; //~ ERROR expected `while`, `for`, `loop` or `{` after a label
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let x = 1;
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let _i = 'label: match x { //~ ERROR expected `while`, `for`, `loop` or `{` after a label
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0 => 42,
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1 if false => break 'label 17,
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1 => {
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if true {
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break 'label 13
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} else {
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break 'label 0;
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}
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}
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_ => 1,
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};
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let other = 3;
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let _val = 'label: (1, if other == 3 { break 'label (2, 3) } else { other }); //~ ERROR expected `while`, `for`, `loop` or `{` after a label
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}
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@ -1,17 +1,75 @@
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error: expected `while`, `for`, `loop` or `{` after a label
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--> $DIR/recover-labeled-non-block-expr.rs:2:13
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--> $DIR/recover-labeled-non-block-expr.rs:4:21
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LL | 'label: 1 + 1;
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LL | let _ = 'label: 1 + 1;
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| ^ expected `while`, `for`, `loop` or `{` after a label
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error[E0308]: mismatched types
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--> $DIR/recover-labeled-non-block-expr.rs:4:33
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LL | let _recovery_witness: () = 0;
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| -- ^ expected `()`, found integer
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| |
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| expected due to this
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help: consider removing the label
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LL - let _ = 'label: 1 + 1;
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LL + let _ = 1 + 1;
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error: aborting due to 2 previous errors
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error: expected `while`, `for`, `loop` or `{` after a label
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--> $DIR/recover-labeled-non-block-expr.rs:6:13
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LL | 'label: match () { () => {}, };
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| ^^^^^ expected `while`, `for`, `loop` or `{` after a label
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help: consider removing the label
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LL - 'label: match () { () => {}, };
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LL + match () { () => {}, };
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error: expected `while`, `for`, `loop` or `{` after a label
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--> $DIR/recover-labeled-non-block-expr.rs:7:13
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LL | 'label: match () { () => break 'label, };
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| ^^^^^ expected `while`, `for`, `loop` or `{` after a label
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help: consider enclosing expression in a block
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LL | 'label: { match () { () => break 'label, } };
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| + +
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error: expected `while`, `for`, `loop` or `{` after a label
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--> $DIR/recover-labeled-non-block-expr.rs:9:13
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LL | 'label: match () { () => 'lp: loop { break 'lp 0 }, };
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| ^^^^^ expected `while`, `for`, `loop` or `{` after a label
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help: consider enclosing expression in a block
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LL | 'label: { match () { () => 'lp: loop { break 'lp 0 }, } };
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| + +
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error: expected `while`, `for`, `loop` or `{` after a label
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--> $DIR/recover-labeled-non-block-expr.rs:12:22
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LL | let _i = 'label: match x {
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| ^^^^^ expected `while`, `for`, `loop` or `{` after a label
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help: consider enclosing expression in a block
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LL ~ let _i = 'label: { match x {
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LL | 0 => 42,
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LL | 1 if false => break 'label 17,
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LL | 1 => {
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LL | if true {
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LL | break 'label 13
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...
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error: expected `while`, `for`, `loop` or `{` after a label
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--> $DIR/recover-labeled-non-block-expr.rs:26:24
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LL | let _val = 'label: (1, if other == 3 { break 'label (2, 3) } else { other });
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| ^ expected `while`, `for`, `loop` or `{` after a label
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help: consider enclosing expression in a block
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LL | let _val = 'label: { (1, if other == 3 { break 'label (2, 3) } else { other }) };
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| + +
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error: aborting due to 6 previous errors
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For more information about this error, try `rustc --explain E0308`.
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